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Why are the elements placed in specific places on the periodic table? 2. periods are rows that run from left to right . 3. elements in the same period have the same number of orbitals. 4. every element in the first period has 1 shell for its electrons. every element in the second period has 2 for its electrons. see the pattern? 5. groups are columns that run from top to bottom. 6. the elements of a group have the same number of valence electrons in their outer shell. 7. every element in group one has 1 electron in its outer shell. every element in group two has 2 electrons in its outer shell. 8. hydrogen is special because it can act like two groups, 1 and 7 . 9. hydrogen sometimes is missing an electron and sometimes it has an extra electron. 10.although helium has only __________ electrons in its outer shell, it is grouped with elements that have ________________?

Respuesta :

The elements are placed in specific places on the periodic table based on their atomic number and outer electronic configuration which gives them certain properties.

The elements of same groups have same number of valence electrons.

Group 1: one electron in valence shell

Group 2: two electrons in valence shell.

Helium has only two electrons in its outer shell and it is grouped with elements that have completely filled outer orbitals, noble gas.